Yellow Dock (Rumex crispus) is a traditional herbal bitter historically used by English herbalists. Yellow dock herb is native to Europe and Asia and grows throughout North America as a common weed. The part used for medical purposes is the root which contains anthraquinones and could be helpful for mild cases of constipation.

Availability as a supplement
Yellow dock comes in sold as a capsule, tincture, tea and dried herb. See herb for a list of medicinal herbs.

Human studies
As of April 2009, published human studies could not be found.

Chemical composition of Yellow Dock
From the roots of yellow dock, anthraquinones and anthrones have been isolated. Extracts of both the leaves and seeds of yellow dock have shown high antioxidant activities.

Fungicidal activity of Yellow Dock root
The methanol extracts of Achyranthes japonica (whole plant) and Rumex crispus roots at concentrations greater than 11 g fresh weight of plant tissue per litre of aqueous Tween 20 solution effectively controlled the development of barley powdery mildew caused by E graminis f sp hordei in an in vivo assay using plant seedlings. At a concentration of 300 g fresh weight of plant tissue per litre of Tween 20 solution, the two extracts were as efficient as the fungicide fenarimol and more active than the fungicide polyoxin B against Sphaerotheca fuliginea on cucumber plants in glasshouse trials.

Yellow Dock root toxicity
Fatal poisoning by Rumex crispus (curled dock): pathological findings and application of scanning electron microscopy.
Vet Hum Toxicol. 1990 Oct;32(5):468-70. Department of Public Health, School of Medicine, University of Barcelona, Spain.
A case of fatal poisoning due to ingestion of the plant Rumex crispus (curled dock) is described. The patient, a 53-year-old male, presented with gastrointestinal symptoms, severe low blood calcium levels, metabolic acidosis and acute hepatic insufficiency. Despite therapeutic measures, the patient died 72 h after ingestion of the plant material. Noteworthy among the pathological findings were centrolobular hepatic necrosis and birefringent crystals in the liver and kidneys that were identified by histochemical techniques and scanning electron microscopy. These observations are compared with other reports in the medical literature, with an emphasis on the risk involved in the use of these plants for culinary or medicinal purposes.